This invention relates generally to a rotary switch, more particularly, to a rotary switch that can create multiple sets of circuit signals by using a rotary dial that has a plurality of multiple sets of contacts that engage with other associated contacts on a circuit board.
FIG. 1 illustrates a previous application dated May 3, 2000 and numbered Ser. No. 09/563,344 seeking for patent, regarding an improved rotary switch proposed by the present inventor.
The previous rotary switch comprises a rotary dial 106, a housing 103 as a platform that supports the rotary dial 106, a contact plate 102 disposed in the housing 103 and arranged so as to rotate with said rotary dial 106, and a circuit board 101 rigidly attached to said housing 103. A shaft contact portion 132 and a contact member array 112 are arranged on the circuit board 101. The contact plate 102 has a plurality of contact protrusions 122 on a surface of said contact plate 102 facing the circuit board 101 and arranged in a predetermined pattern so as to communicate in a variety of settings with said contact member array 112. A user applies a force on the rotary dial 106 to rotate the contact plate 102 to enable some of the contact protrusions 22 to press and contact some of the contact members of the contact member array 112 to create different circuit signals. The user then depresses an operating shaft 105 to enable the shaft contact portion 111 to effect a circuit for output the mentioned circuit signals so that multiple circuit signals and two-stage control are made possible.
Some problems arise with the mentioned rotary switch:
1. Clearance between the rotary dial 106 and the housing 103 is excessive, and the rotary dial 106 is liable to skew under operation. PA1 2. It is difficult to correctly assemble the rotary switch so that there is conformity between software and the alignment of the shaft contact portion to prevent erroneous commands. PA1 3. As a result of the configuration of the assembled switch, circuit layout on the circuit board is difficult and hence, a secondary processing job is required. PA1 4. The protruding section of the shaft contact portion wears out easily due to the rigidity of the operation shaft 105. Moreover, as the operation shaft 105 lacks positioning design, it may be inadvertently moved by the rotary dial. PA1 5. Molding is difficult for the complicated structure of a resilient indexing ring 104 and a plurality of slide-guiding grooves disposed between the rotary dial and the housing. Further, when the rotary dial is skewed, the indexing ring 104 will be inevitably deformed and hinder operation of the rotary switch. PA1 1. A plurality of circular support projections extending from a side of a rotary dial that communicate with the housing so as to prevent skew of the control panel when rotating. PA1 2. An indexing band frame arranged on the rotary dial for holding an indexing band that communicates with a plurality of axially extending cams separated by grooves and spaced circumferentially around a central through hole on the housing. The indexing band has a central ridge that engages with the cams so as to index the rotation of the rotary dial and provide an audible click when the rotary dial is rotated. PA1 3. A resilient bushing made of a material with lesser rigidity, such as rubber or plastics, is received by the operation shaft, and contacts the shaft contact portion. The resilient bushing prevents less wear on the shaft contact portion. A mutual terminal and a plurality of connecting terminals are adopted for transmission of more distinct output signals. PA1 4. A binding member extending from the rotary dial has a side lug that is received by a contact plate. The operation shaft has two diametrically opposed wing protrusions extending radially from the lower end. The wing protrusions are received by two grooves formed by the circuit board to provide for alignment during assembly and to avoid erroneous instructions. PA1 5. The operation shaft comprises a notch located at a top end for receiving an press button. The rotary dial is arranged to receive a turntable to cover the side opposite to the side facing the housing. The circuit board has a plurality of fixing feet adapted for installation on an electronic device.